An alternative is to use one of many graphical user interface applications like QuickHash

Tests

Testing FileReader

Testing MD5 in browser

Testing SHA1 in browser

Why calculate checksum?

MD5 and SHA1 are used to calculate fingerprint of large amount of data, i.e they map something with a lot of
bits to just a few bits (128 in case of MD5 and 160 in case of SHA1).

This is useful because one can compare these small hashes of the downloaded file with the hash provided by
trusted source to make, reasonably safe assumption, that downloaded file is the same as original file.

Why calculate checksum using MD5?

MD5 is popular one way hash function developed by R. Rivest in 1991. It is commonly used to verify data
integrity of file downloads. While flaws have since been found it is still widely used as to fingerprint
files on the web. Supplementing MD5 hash with SHA1 greatly reduced MD5 weaknesses.

Why calculate checksum using SHA1?

SHA1 is designed by NSA and standardized by NIST. While collision attach theoretically exists in SHA1 it has not
yet been demonstrated (as of early 2014). SHA1 produces 160 bit fingerprint. It is widely used on the web,
althrough less widely than MD5 as a fingerprint for downlaods. Additionally SHA1 is used to ensure integrity in
many other systems including GIT.

Calculating MD5 checksum and SHA1 checksum on Microsoft Windows?

On Windows there are few options to calculate MD5 and SHA1 checksums.
Microsoft provides File Checksum Integrity Verifier (FCIV) utility.